Black swans: challenging the relationship of anaesthetic-induced unconsciousness and electroencephalographic oscillations in the frontal cortex

The study of general anaesthesia and electroencephalographic oscillations in the frontal cortex spans at least four decades, with several notable findings:In 1977, Tinker and colleagues1 proposed, based on studies of the nonhuman primate, that anteriorization —the shift of electroencephalographic power from posterior cortex to frontal cortex—correlated with unresponsiveness during general anaesthesia.In the early 1990s, Steriade contributed to our understanding of the neurophysiology of sleep and general anaesthesia in animals, including descriptions of three distinct oscillations involving corticothalamic networks: a slow rhythm at  <  1 Hz, a delta rhythm at 1-4 Hz, and a faster theta/alpha rhythm at 7-14 Hz.23In the mid-1990s, the shift of alpha oscillations to more anterior structures was identified during both propofol sedation4 and isoflurane/nitrous oxide anaesthesia.5In 2001, anteriorized alpha and slow-wave activity was posited by John and colleagues6 to be an agent-invariant marker of anaesthetic-induced unconsciousness, based on a study of 176 surgical patients.In 2004, the disappearance of occipital alpha oscillations and shift to high-power frontal alpha oscillations was found to be associated with propofol-induced unconsciousness in healthy human participants.7In 2013, Purdon and colleagues8 found, using high-density electroencephalography in human volunteers, that anteriorization of alpha and phase-amplitude coupling patterns correlated with pr...
Source: British Journal of Anaesthesia - Category: Anesthesiology Source Type: research